The present invention relates to retaining wall blocks and walls made from such blocks. In particular, this invention relates to retaining wall blocks having pin receiving cavities, pin holes, and cores arranged to maximize the strength of the block and walls made therefrom.
Numerous methods and materials exist for the construction of retaining walls. Such methods include the use of natural stone, poured in-place concrete, pre-cast concrete, masonry, and landscape timbers or railroad ties. In recent years, segmental concrete retaining wall units which are dry stacked (i.e., built without the use of mortar) have become a widely accepted product for the construction of retaining walls. Examples of such products are described in U.S. Pat. No. Re. 34,314 (Forsberg ""314) and U.S. Pat. No. 5,294,216 (Sievert). Such products have gained popularity because they are mass produced, and thus relatively inexpensive. They are structurally sound, easy and relatively inexpensive to install, and couple the durability of concrete with the attractiveness of various architectural finishes.
The retaining wall system described in Forsberg ""314 has been particularly successful because of its use of block design that includes, among other design elements, a unique pinning system that interlocks and aligns the retaining wall units, allowing structural strength and efficient rates of installation. This system has also shown considerable advantages in the construction of larger walls when combined with the use of geogrid tie-backs hooked over the pins, as described in U.S. Pat. No. 4,914,876 (Forsberg).
The construction of modular concrete retaining walls as described in Forsberg involves several relatively simple steps. First, a leveling pad of dense base material or unreinforced concrete is placed, compacted and leveled. Second, the initial course of blocks is placed and leveled. Two pins are placed in each block into the pin holes. Third, core fill material, such as crushed rock, is placed in the cores of the blocks and spaces between the blocks to encourage drainage and add mass to the wall structure. Fourth, succeeding courses of the blocks are placed in a xe2x80x9crunning bondxe2x80x9d pattern such that each block is placed between the two blocks below it. This is done by placing the blocks so that the receiving cavities of the bottom of the block fit over the pins that have been placed in the units in the course below. As each course is placed, pins are placed in the blocks, the blocks are corefilled with drainage rock, and the area behind the course is backfilled and compacted until the wall reaches the desired height.
If wall height or loading conditions require it, the wall structure may be constructed using reinforced earth techniques such as geogrid reinforcement, geosynthetic reinforcement, or the use of inextensible materials such as steel mesh or mat. The use of geogrids are described in U.S. Pat. No. 4,914,876 (Forsberg). After placement of a course of blocks to the desired height, the geogrid material is placed so that the pins in the block penetrate the apertures of the geogrid. The geogrid is then laid back into the area behind the wall and put under tension by pulling back and staking the geogrid. Backfill is placed and compacted over the geogrid, and the construction sequence continues as described above until another layer of geogrid is called for in the planned design. The use of core fill in the blocks is known to enhance the wall system""s resistance to pull out of the geogrid from the wall blocks.
Block designs known in the art have typically not maximized the amount of core fill in a retaining wall because the block shape and core design do not permit this. Use of maximum amount of core fill was thought to be a way to strengthen a retaining wall and minimize problems with geogrid pull out. A block designed to maximize the amount of core fill due to alignment of blocks in a wall, whether the blocks are in a running bond pattern or stacked directly on top of and aligned with each other is described in commonly assigned, co-pending U.S. patent application Ser. No. 09/312,352 (filed May 14, 1999) entitled xe2x80x9cRetaining Wall Blockxe2x80x9d. The blocks have a core, pin receiving cavities and pin holes. The pin receiving cavities are on the bottom of the blocks and engage pins placed in the pin holes of a block on a lower course of blocks in a wall. The pin receiving cavities extend approximately one inch into the bottom surface of the blocks and do not extend through the thickness of the block from bottom to top. The arrangement of the pin holes and pin receiving cavities in a plane parallel to a plane of symmetry permits formation of walls with predetermined set back, ease of construction, good alignment of cores and improved strength due to core-filling. These blocks are typically manufactured, loaded onto pallets and shipped with the pin receiving cavities facing up. Therefore, when a retaining wall is assembled with these blocks they must be flipped over by the installer so that the bottom of the block faces downward.
However, it is desirable to facilitate construction methods of retaining walls as well as to optimize the strength of retaining wall blocks. Improved strength is an advantage not only during construction of retaining walls but during manufacture of the block.
It has been discovered that pin holes and pin receiving cavities can be arranged on a block to result in a stronger block and a stronger wall made from such blocks. The pin receiving cavities penetrate the thickness of the block, providing for easier construction of a wall as well as reduced weight for the block.
In one aspect, this invention is a retaining wall block comprising a top surface; a bottom surface substantially parallel to the top surface; first and second side surfaces; a front face; and a rear face; the front and rear faces, top and bottom surfaces and side surfaces defining a body portion including the front face, a head portion including the rear face, and a neck portion connecting the body portion and the head portion, the neck portion including a first portion of the first side surface and a first portion of the second side surface, the first portion of the first side surface lying substantially within a first plane, the first portion of the second side surface lying substantially within a second plane, the neck portion being configured such that intersections of the first and second planes with the body portion define first and second corner portions of the body portion, the body portion including first and second pin holes opening into the top surface and first and second pin receiving cavities extending through the body portion and opening into the top surface and the bottom surface, the pin receiving cavities being positioned such that no substantial portion of the cavities lies within the first and second corner portions.
The neck portion may include an opening extending through the neck portion from the top surface to the bottom surface, the opening dividing the neck portion into first and second neck wall members extending rearwardly from the body portion to the head portion. The body portion may also comprise third and fourth pin holes opening onto the top surface. The side wall faces may taper from the front face to the rear face. The head portion may have first and second ears extending laterally beyond the first and second neck wall members, respectively, the first and second ears each being provided with a notch to enable the ears to be knocked off the head portion.
In a second embodiment, this invention is a retaining wall comprising at least one lower course and at least one upper course, each course comprising a plurality of blocks laid in a running bond pattern, and comprising the block described above. First and second pins are disposed in the first and second pin holes, respectively, of a block in the lower course, the first pin having a first free end protruding beyond the top face of the block, the second pin having a second free end protruding beyond the top face of the block, the first free end being received in a pin receiving cavity of a first block in the upper course, the second free end being received in a pin receiving cavity of a second block in the upper course, and a continuous cavity is defined by each opening of vertically aligned blocks in the upper course of the blocks communicating with side voids of vertically adjacent blocks in the lower course.
The wall may be straight, curved, or serpentine and may further comprise rebar and grout, wherein a length of the rebar passes through the continuous cavity and is secured with the grout. The wall may also comprise at least one post extending into the continuous cavity and protruding from the upper course, the at least one post being secured in the cavity with grout and/or a geogrid tie-back disposed between the upper and lower courses, the geogrid tie-back having apertures and being secured with at least one of the first and second pins passing through the apertures thereof. The retaining wall may also include a pilaster formed of a column of the blocks set forward from the remainder of the wall.